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Plug-in hybrid electric vehicles emit almost 5x greater global warming emissions than official figures show, according to a recent analysis.

Growing Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel vehicles, according to research conducted by a non-profit group. This differs significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” stated a lead analyst participating in the study. “That gap is growing and poses a serious problem. As a result, PHEVs emit almost as much as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total distance. They determined that just a quarter of travel was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in electric mode, emission levels were significantly higher than official estimates. That occurred because EV motors were not strong sufficient to operate independently, leading to engines burning fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV CO2 output allowed four large automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 more annually in operating costs than would be estimated under laboratory tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously far from the truth,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the car sector and opposition from member states with large car manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “compromise” solution to include in the legislation.

One external energy policy specialist, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was too little data to accurately evaluate actual emissions.

“The results show, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert stated. “All regulatory changes concerning PHEVs should be made with extreme caution and in the light of that evidence.”